Treatment of montan wax



Patented Feb. 26, 1952 UNITED STATES PAT NT QFFICE TREATMENT OF MONTANWAX No Drawing. Application August 18, 1949-, Serial No. 111,089

12 Claims. 1

This invention relates to the treatment of montan wax. More particularlythe invention relates to the production of hard gel-free waxes frommontan wax by a process including partial esterificationof montan waxwith a dihydric alcohol followed by esterification of the remaining freecarboxyl groups by means of a higher p01yhydric alcohol such as onecontaining from 3 to 8 hydroxy groups.

Montan wax is a product which is generally obtained from brown coal. Onemethod of producing this material ,includes granulating brown coal anddrying the resulting granulated material to a moisture content of about10% to 12%. The granules are then sieved to remove any powder therefrom,and the powder-free granules are extracted with a mixture containingabout 85% benzol and 15% unrefined wood alcohol containing methyl andisopropyl alcohols. This extraction is normally carried out at atemperature of about 90 C. to 100 C. The alcohols dissolve the cellwalls of the brown coalgranules and free the wax therefrom, therebyenabling the wax to be dissolved by the benzol. The .wax solution isseparated; and the solvent distilled off, leaving the crude montan waxas a residue.

This crude montan wax is comprised essentially of resin acids, fattyacids, and wax esters similar to those contained in carnauba wax. Thesimilarity to carnauba wax is due to the presence of a mixture of estersof acids of high molecular weight containing 26 to 29 carbon atoms,primarily carboceric and montanic acid with 27 and 29 carbon atomsrespectively with alcohols such as n'iacontyl (CsuHmOI-I) and the like.Weprefer to employ a wax which has been partially deresinified.

The crude montan waxes are somewhat limited in their :utility because ofthe dark color which characterizes these materials.

Various methods have been proposed and used to produce a montan wax ofsufficiently light color to enable its use in those instances wherelight color is required. These bleaching proc 2 ing bleached montan waxto esterify the fattyacid content thereof, but considerable difficultyhas been experienced in producing a desirable material by followingthese methods.

Among the methods which have been proposed is one involving theesterification of bleached montan wax with a dihydric alcohol, such asethylene glycol, butylene glycol, polyethylene glycol, and the like, Theesterified products show a hardness as measured by the Sward rockermethod which is substantially below ca nauba Wax. When penterythritoland similar high poly,- hydric alcohols are used to esterify bleachedmontan wax, the products contain a substantial amount of gelledmaterial. While we do not intend to be limitedto any theories expressedherein, it is believed that the production of gels in the esterificationof montan wax with pentaerythritol is due to the formation of dibasicacids during the bleaching of the montan wax by means of oxidizingagents. These dibasic acids form polycondensation products of networkstructure with the higher polyhydroxy alcohols such as pentaerythritol.

In order to overcome the tendency towardgel formation in the treatmentof montan wax,mix tures of higher polyhydroxy alcohols and glycolsweretried; but the products either contain a substantial amount of gelor are comparatively soft materials and cannot be used in formulationswherein a hardness such as that of carnauba wax is required.

We have found that hard and gel-free readily dispersible waxes can beobtained from bleached montan wax by means of a process in which thebleached Wax is first treated with a glycol to partially esterify themonocarboxylic acids and to convert a substantial quantity of thedibasic acids to mono-esters and. thereafter esterifying the remainingfree carboxyl groups with ahigher polyhydric alcohol containing, forexample, 3 to 8 hydroxy groups, such as pentaerythritol. The resultingwaxes show a hardness about equal to that of carnauba wax and, inaddition, are free from gelled products.

In the initial esterification step of our proc ess we may employ any ofanumber of dihydric alcohols to accomplish the partial esterification ofthe dicarboxylic acid content of the bleached montan Wax. Typical of thedihydroxy alcohols are ethylene glycol, butylene glycol, diethyleneglycol, propylene glycol, and the like. Generally Speaking, we fin itadvantageous to utilize unsubstituted dihydroxy alcohols in carrying"out this phase of our process. However, it willbeapand trimers ofpentaerythritol.

parent to those skilled in the art that the dihydroxy alcohol maycontain any substituents which do not interfere with the esterificationof the dicarboxylic acid groups contained in the montan wax or thedesired properties of the final product.

As to higher polyhydric alcohol, we have advantageously employedpentaerythritol which may be in a highly purified form or which may be acommercial product containing some dimers Of course, other polyhydricalcohols, such as glycerol, dipentaerythritol, tripentaerythritol,sorbitol, mannitol, and the like may be used. In this phase of ourprocess we have obtained advantageous results by utilizing unsubstitutedpolyhydric alcohols containing 3 to 8 hydroxy groups; but if desired, wemay employ polyhydric alcohols having 3 to 8 hydroxy groups andcontaining substituents which do not interfere with the esterificationof the remaining free carboxyl groups in the montan wax. Thesesubstitute materials are well known to those skilled in the art.

While the bleached montan wax may be obtained by any of a number ofwell-known bleach: ing processes, we prefer to employ a bleached waxobtained by heating the wax with sulfuric acid to obtain a wax emulsionand thereafter treat the emulsion with a mixture of chromic acid andsulfuric acid or with chromic acid alone. The resulting product is quitelight in color; and hence, its field of use when treated in accordancewith our invention is widened.

In order to more fully understand our invention, reference may be had tothe following specific examples which are given by way of illustrationand not by way of limitation.

. In Example I we describe our preferred method of obtaining thebleached wax which is treated in-accordance with our invention.

Example I 100 grams of montan wax were placed in a 2-liter, 3-neck roundbottom flask seated in an electrically heated mantle and fitted with amechanically operated stirrer, dropping funnel, and thermometer. To thiswere added 400 ml. of a 47% aqueous sulfuric acid solution, and thewhole was heated to 105 C. Stirring Was begun as soon as the wax becamemolten. The mixture formed a homogeneous, emulsified mass withinminutes. Therewas then added dropwise over a, 30-minute period asolution of 100 grams of chromium trioxidein 100 ml. of water. Duringthis time the temperature of the reaction mixture was maintained at 110C. to 112 C. (The heat of reaction was suflicient to maintain thistemperature during the first minutes.) After the addition of the oxidantwas complete, stirring was continued for another minutes at 110 C. to112 C., and 100 ml. of boiling water were added to break the emulsion.Heating was discontinued and the contents of the flask were allowed tostand and cool. Upon separation and subsequent solidification of the waxlayer, the dark, green aqueous phase was poured off. The

wax was then washed with 400 ml. of 47% sulfuric acid by stirringvigorously at 95 C. to 100 C. for 20 minutes. Upon cooling andseparation of the wax, the wash acid was removed, and the wax washedwith two 1 liter portions of water at boil for 20 minutes each. Afterremoval of the wash water, the wax was dried by heating with stirring ata temperature of 90 C. to 95 C. and a pressure of 160 mm. until allfoaming v minutes.

ceased; the wax became clear, and the temperature began to rise sharply.The cooled product was brown colored and showed a reflectance of 6% at600 mu. as determined on a General Electric recording spectrophotometer.It had a melting point of 79 C. to 84 C. and an acid number of 123. Theyield was 62.8 grams or 62.8%. A further bleaching treatment of theproduct obtained using the same amounts of reactants and the sameprocedure gave a light-colored product (36% reflectance), having an acidnumber of 170 and a melting point of 76 C. to C. The overall yield was54.2%.

With larger quantities of reactants higher yields can be obtained.

The following examples are illustrative of the process of our invention.The esteriflcation reactions described in the examples given below werecarried out in a 4-neck round bottom flask fitted with a mechanicallyoperated stirrer, thermometer, and gas inlet tube. During the reactionof glycols with wax acids an electrically heated reflux condenser wasalso attached. The temperature of this condenser was maintained at alevel sufficient to prevent condensation of water vapor, but Well belowthe boiling point of the glycol, and served to reduce the loss ofglycol. After completion of the glycol esterification the condensercould be removed. The gas inlet tube served to permit the constantintroduction of an inert gas such as carbon dioxide or nitrogen. The useof these gases effected the dual function of acting to sweep out thewater of reaction and to provide a nonoxidizing atmosphere to reducecoloration.

Example II grams (0.28 equivalent of wax acids) of bleached montan wax(acid number 160), 8.7 grams (0.28 equivalent) of ethylene glycol, and0.50 gram p-toluene sulfonic acid were melted together in the apparatusdescribed above and heated at C. to 112 C. with constant agitation in astream of nitrogen gas (about 0.4 liter per minute) until (four hours)successive acid number determinations indicated substantially all of theglycol had been esterifled. The acid number of this partially esterifledwax was 34.1. 50 grams (0.031 equivalent of wax acids) of this materialwere then allowed to react with 1.1 grams (0.030 equivalent) oftechnical grade pentaerythritol (commercially available as Pentek) byheating to 170 C. until the pentaerythritol was dissolved. This tookabout 5 to 10 The reaction was continued at C. to C. with stirring, andnitrogen gas was passed through the reaction zone in" the mannerindicated above. After six hours the esterification was substantiallycomplete, and the acid number of the product was 4.2. The wax was hard,light brown colored, and had a melting point of 75 C. to 80 C. asdetermined on a Fisher-Johns melting point determination stage. TheSward hardness of a molded sample of the wax was 15.

Example III The flask was charged with 50.0 (about 0.15 equivalent ofwax acids) of bleached montan wax (acid number 2.4 grams (0.077equivalent) of ethylene glycol, and 0.25 gram of p-toluene sulfonicacid. The mixture was heated slowly to melt the wax and then heated at150 C. to 160 C. with continual stirring and passage of nitrogen gasthrough the reaction zone at a rate Example IV 150.0 grams (0.43equivalent of wax acids); of bleached montan wax. (acid number160),,15.1 grams (0.49 equivalent) of ethylene glycol, and 0.75 gramp-toluene sulfonic acid wereheated at 108- C. to 112 C. with constantstirring under nitrogen gas for five hours. The acid number leveled offat 24.4. To 50 grams of: this material there was added 0.80 gram, (0.022equivalent) of pentaerythritol and the temperature raised to andmaintained at 170 C. to 180 C. After six hours acid numberdeterminations indicated that substantially all of the pentaerythritolhad been esterified. The product was a light brown col.- ored wax with amelting point of 75 C. to 80 C. and had a Sward hardness of 18. Thefinal, acid number was 16.0. r

In. another embodiment. of our invention the bleached montan wax may be.treated with adihydric alcohol as above described to esterify thedibasic acids and thereafter treated with pentaerythritol or otherhigher polyhydric alcohols; After substantially all of the carboxylicacids have been esterified, minor portions of an unsaturateddicarboxylic acid or anhydride thereof may be added. The unsaturateddicarboxylic acid may be maleic acid or its anhydride and any otherunsaturated dicarboxylic acid or an hydride thereof similar to maleicacid may be used, for example, itaconic acid, fumaric acid, phthalicacid, and the like. We prefer to employ unsubstituted unsaturateddicarboxylic acids; but if desired, any substituted acid may be usedwhich does not contain substituents which would interfere with thedesired reaction. Waxes obtained by this embodiment of our invention areparticularly suitable for use in the preparation of emulsion. fioorpolishes. This embodiment of our invention is illustrated in thefollowing specificv examples.

Example V t 50. grams (0.141 acid equivalent) of bleached montan wax(acid number 170) were partially esterifled by treating with 4.8 grams(0.155 equivalent). of ethylene glycol in the presence of 0.25 gram ofp-toluene sulfonic, acid at 110 C. to 115 C. for five hours. Nitrogengas and agitation were utilized as described in Example '11. The acidnumber reached 14.8. There was then added 0.65 gram (0.019 equivalent)of pentaerythritol and the mixture heated to 175 C. and held there untilthe pentaerythritol dissolved. This occurred in about minutes. Thecontents of the flask were then cooled to 110 C. and the reactioncontinued at 110 C. to 115 C. for 1.5 hours. 0.44 gram (.009 equivalent)of maleic anhydride was then added, and the mixture heated for eightmore hours. The product was a light brown, colored wax with acid numberof 9.28, a. melting point of 73 C. to 80 C., and a Sward hardness of 19.

Example VI scrlbedinExampleN and 1.0 gram (0.027 equiv? alent) ofpentaerythritol were allowed to react. The temperature of the: reactionmixture was raised to 170 C. and the reaction continued at. thattemperature for thirty minutes (acid number 18.1). To the mixture therewas then added 0.5 gram (0.011 equivalent) of maleic anhydride. Heatingwascontinued at 170 C. to 180 C. for sixhours. The product. wasa hard,light brown wax with an acid numberof 4.35, a melting point of 77 C; to80 0., and a Sward hardness; of

17. Example VII 360 grams (1.09 equivalents) of bleached montan wax(acid number 170). 24.6 grams (0.79 equivalent) ofv ethylene. glycol,and, 2.0 grams ptoluenesulfonic acid were heated at 108 C. to 112 C;(with mechanical agitation and a stream of carbon dioxide gas. at therate. of 0.7 liter per minute) for 1.5jhours (acid number 72.3). 10.28

grams (0.28 equivalent) of pentaerythritol were added and thetemperature of the mixture was raised to 200 C. and held there for 25minutes. The temperature was, then raised to 250 C. and held there for 5minutes. The mixture was. cooled to and 3.52 grams (0.072 equivalent) ofmaleic anhydride were added. The reaction was continued at C. to C. forthree hours, (acid number 20.5). duced was light brown in color and hadagSward hardnessof 16 and a melting point, of 71 C. to 75C.

Example. V;III-' 50 grams of bleached montan wax partially esterified(acid number 24.2) with: ethylene glycol as described in Example IV and2.29 grams (0.052 equivalent) of dipentaerythritol (Dipentek) wereadded. The mixture was heated at 200 C; to 210 C..for one hour whilebeing stirred. A stream of carbon dioxide gas was passed through at therate of 0.4 liter per minute. The acid number dropped tov 9.40. At thispoint the reaction mixture was cooled to 150 C., and 1.47 grams (0.030equivalent) of maleic anhydride were added. Heating, was continued at200 C. for two hours. The product was brown in colorand hard, showing. aSward hardness of 16. The acid number was 5.52 and the melting point was76 C; to 82 C.

The waxes obtained in accordance with our invention may be emulsified byany'of the methods known to the art. A, typical formulation isillustrated in the following example:

Example IX 10 grams of the waxobtained in accordance with Example VII,1.4 grams of oleic acid, and 1.4 grams of triethanolamine were heated ona steam cone until the temperature was 92 C. With'constant stirring 80grams of boiling water were slowly added. The emulsion was then cooledto room temperature with stirring. A bright drying emulsion was obtainedwhich was adapted for use as a fioor polish.

While our invention may be practiced utilize ing various quantities of.dihydric alcohol and higher polyhydricalcohol, we have found that inorder to definitely avoid gel formation the ratio on a stoichiometricalequivalent basis of polyhydric alcohol to; dihydric alcohol should be inthe range of about 0.2 to about 0.8 part of higher polyhydric alcohol toabout 1 part of dihydrio alcohol. Within these limits of 0.2. to 0.8equivalent or higher polyhydric alcohol to 1 equiva- The wax prqlent ofdihydric alcohol, the higher ratio will apply to the minimum allowablepercentage of wax acids esterified in the first step and the lowerratios will apply in those instances where higher percentages of waxacids are esterified in the first step. In other words, when a higherpercentage of wax acids is esterified in the first step, lesserquantities of higher polyhydric alcohol are required for substantiallycomplete esterification; and when a lower percentage of esterification'is obtained, greater quantities of higher polyhydric alcohol arerequired in the second step. When maleic anhydride or equivalentdicarboxylic acid material is employed in conjunction with glycol andhigher polyhydric alcohol, the ratio is advantageously 0.01 to' 0.07p'art maleic anhydride, 0.14 to 0.4 higher polyhydric alcohol, and about1 part of dihydric alcohol. In the three-stage process, we have found itadvantageous to use approximately a twenty-five percent excess ofpolyhydric alcohol to provide sufiicient hydroxyl groups for subsequentesteriilcation with dicarboxylic acid. Although materials having somedesirable characteristics may be prepared utilizing the reactants inproportions outside of the ranges set forth, products having lessdesirable properties are obtained. In our two-stage process gelformation is overcome by reacting at least 38% of the waxacid withdihydric alcohol and reacting the remaining groups with higher alcohol.We have obtained hard gel-free waxes in a three-stage process byreacting the dihydric alcohol with bleached montan wax untilat least 55%of the wax acids have been reacted as evidenced by the acid number. Theresulting material is then reacted with the higher alcohol untilsubstantially all of the acid groups have been esterified. Maleicanhydride or its equivalent is added after the high. er alcohol in thisembodiment.

Generally speaking, in the practice of our invention the esterificationreactions are advantageously carried out at a temperature between about105 C. and about 225 C. Ordinarily we prefer to employ temperatures ofabout 105 C. to 140 C. as the lower temperatures within this range yieldlighter colored products. If desired, the pressure may be reduced tospeed up the reaction by more rapid removal of the water of reaction. Itis also within the scope of our invention to carry out the reaction inthe absence of an inert gas at temperatures up to 140 C. without thedevelopment of excess color. This is generally practiced when asubstantially completely pure higher polyhydric alcohol is utilized.When technical grade materials are employed;

it is generally desirable, if not necessary, to heat.

at higher temperatures in order to get these materials in solution. Forexample, using a technical grade pentaerythritol we find operation attemperatures of about 170 C. would be desirable.

While we have illustrated and described our invention with reference tocertain particular embodiments and with reference to certain speciflcexamples, it is to be understood that the invention is not limitedthereby. Therefore. changes, omissions, substitutions, and/or additionsmay be made without departing from the spirit of the invention asdefined in the appended claims which are intended to be limited only asrequired by the prior art.

We claim: g

1. A process of producing a hard waxy material from bleached montan waxcomprising metrical equivalent basis.

esterifying a portion of the acid content of the bleached wax usingdihydric alcohol, and thereafter esterifying substantially all of theremaining free carboxyl groups with a higher polyhydric alcohol.

2. The product of the process of claim 1. 3. A process of producing ahard readily dispersible wax from bleached montan wax comprisingesterifying at least a portion of the acids of said wax with a dihydricalcohol, heating the resulting material in the presence of a higherpolyhydric alcohol to esterify substantially all of the remaining freecarboxyl groups, and thereafter reacting the resulting material byheating in the presence of an unsaturated dicarboxylic acid.

4. The product of the process of claim 3.

5. A fioor wax preparation comprising an aqueous emulsion of the productof claim 4. 20"

6. A process of producing hard readily dispersible waxes from bleachedmontan wax comprising esterifying the dicarboxylic acid groups in saidwax with ethylene glycol, and thereafter esterifying substantially allof the remaining free carboxyl groups with pentaerythritol.

7. A process of producing a hard readily dispersible wax from bleachedmontan wax comprising heating said wax in the presence of ethyleneglycol to esterify the dicarboxylic acid groups in said wax, heating theresulting material in the presence of pentaerythritol to esterifysubstantially all of the remaining free car-. boxyl groups, andthereafter reacting. the. resulting material with maleic anhydride byheat-v in the presence thereof.

8. A process of producing a hard waxy material from bleached montan waxcomprising esterifying a portion of the dibasic acid content of thebleached wax by means of a dihydric alcohol, and thereafter esterifyingthe remaining free carboxyl groups with a polyhydric alcohol containing3 to 8 hydroxy groups.

9. A process of producing a hard waxy material from bleached montan waxcomprising heating said bleached wax in the presence of a dihydricalcohol to esterify a portion of the dibasic acid content thereof, andthereafter esterifying the remaining free carboxyl groups with apolyhydric alcohol containing 3 to 8 hydroxy groups, the ratio ofpolyhydric alcohol to dihydric alcohol being in the range of about .2 toabout .8 parts of higher polyhydric alcohol to about 1 part of dihydricalcohol on a stoichio- 10. A process of producing hard waxy materialfrom bleached montan wax comprising heating said bleached wax in thepresence of a dihydric alcohol until at least 38% of the wax acids havereacted with said alcohol, and thereafter heating the resulting materialin the presence of a polyhydric alcohol containing 3 to 8 carbon atomsto esterify the remaining free hydroxy] groups, the ratio on astoichiometrical equivalent basis of polyhydric alcohol to dihydricalcohol being in the range of about .2 to about .8 parts of polyhydricalcohol to about 1 part of dihydric alcohol.

11. A process of producing a hard readily dispersible wax from bleachedmontan wax comprising heating said wax in the presence of a dihydricalcohol to esterify a portion of the dibasic acid content thereof,heating the resulting ma-. terial in the presence of a polyhydricalcohol containing 3 to 8 carbon atoms, and thereafter reacting theproduct with an unsaturated dicarboxylic acid, the ratio of theadditives being 0.01

to 0.07 part maleic anhydride, 0.14 to 0.4 of polyhydric alcohol, andabout 1 part of dihydric alcohol on a stoichiometrical equivalent basis.

12. A process of producing a hard readily dispersible Wax from bleachedmontan wax comprising heating said wax in the presence of a dihydricalcohol until at least 55% of the wax acids have been reacted, heatingthe resulting material in the presence of a polyhydric alcohol having 3to 8 hydroxy groups to esterify substantially all of the remaining freecarboxyl groups, and. thereafter reacting the resulting material byheating in the presence of an unsaturated dicarboxylic acid, the ratioof dihydric alcohol, polyhydric alcohol, and dicarboxylic acid on astoichiometrical equivalent basis being 0.01 to 0.07 part REFERENCESCITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,834,056 Guthke et al Dec. 1,1931 2,025,612 Rodman Dec. 24, 1935 OTHER REFERENCES Bennett-CommericalWaxes, 1944, Chem. Pub. 00., Brooklyn, N. Y., page 499.

1. A PROCESS OF PRODUCING A HARD WAXY MATERIAL FROM BLEACHED MONTAN WAXCONPRISING ESTERIFYING A PORTION OF THE ACID CONTENT OF THE BLEACHED WAXUSING DIHYDRIC ALCOHOL, AND THEREAFTER ESTERIFYING SUBSTANTIALLY ALL OFTHE REMAINING FREE CARBOXYL GROUPS WITH A HIGHER POLYHYDRIC ALCOHOL.